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AfterQuery

Category: AI Infrastructure

An applied AI research lab and data platform that curates expert-level, proprietary datasets and reinforcement learning environments to train the next generation of foundation models. AfterQuery was founded in 2024. The company is led by Spencer Mateega. Based in San Francisco, USA. Team size: 10-50. Total funding raised: $30.5M. Latest round: Series A (May 2025). Key investors include ["Altos Ventures","Y Combinator","Break Ventures"].

Founded
2024
Headquarters
San Francisco, USA
Team size
10-50
Total funding
$30.5M

Value proposition

Overcomes the 'data wall' in AI training by providing high-reasoning, professional-grade data from human experts that does not exist on the public internet.

Products and solutions

["Expert-Led Data Curation Pipeline","Reinforcement Learning (RL) Training Environments","Domain-Specific Reasoning Datasets (Medicine, Law, Engineering)","Expert-in-the-Loop Model Evaluation Frameworks"]

Unique value

Focuses on the generation of 'expert reasoning' data rather than simple data labeling, utilizing a network of high-signal professionals (doctors, lawyers, engineers) to create datasets that encode complex decision-making processes.

Target customer

Foundation model labs (e.g., OpenAI, Anthropic, Google), enterprise AI research teams, and companies building domain-specific LLMs.

Industries served

["Artificial Intelligence","Healthcare & Medicine","Legal Services","Finance & Quantitative Research","STEM & Engineering"]

Technology advantage

Combines a proprietary 'Expert-in-the-loop' workflow with reinforcement learning environments to scale human expertise into machine-readable training signals, led by a founding team with elite backgrounds in both Big Tech engineering and Private Equity.

How they differentiate

Focuses on generating 'expert reasoning' data and reinforcement learning environments using a network of high-signal professionals (doctors, lawyers, engineers) to overcome the AI 'data wall' rather than general crowdsourced labeling.

Main competitors

["Scale AI","Surge AI","Labelbox"]

Key partnerships

["Y Combinator (W25 Batch)","Altos Ventures (Lead Series A Investor)","Major foundation model labs (Strategic data partnerships)"]

Notable customers

["OpenAI","Anthropic","Google"]

Major milestones

["Accepted into the Y Combinator Winter 2025 (W25) batch","Closed a $30M Series A funding round led by Altos Ventures in May 2025","Reached a $300M post-money valuation within one year of founding","Established strategic data partnerships with major frontier foundation model labs"]

Growth metrics

Estimated $5M - $10M ARR; achieved a $300M post-money valuation within its first year.

Market positioning

Premium AI data infrastructure lab specializing in expert-in-the-loop datasets for frontier foundation model developers.

Geographic focus

North America (San Francisco-based), serving global foundation model labs.

Patents and IP

No registered patents disclosed; relies on proprietary data curation methodologies and trade secrets.

About Spencer Mateega

Spencer Mateega is the Co-Founder and CEO of AfterQuery. He has a high-signal background in both elite finance and big tech, having completed internships at Silver Lake (Private Equity), Morgan Stanley (Investment Banking), Google, and Meta (Software Engineering). He studied Statistics, Finance, and Computer Science at The Wharton School of the University of Pennsylvania. He is a serial entrepreneur, having co-founded his first startup during high school with his current co-founder, Danny Tang.

Official website: